title: Visual P3 amplitude modulation deficit in schizophrenia is independent of duration of illness.
abstract: BACKGROUND
  In the search for markers of schizophrenia, functional deficits during inhibition have been a major focus. In previous studies, we found a reduced amplitude modulation of the visual P3 component of the event-related potential (ERP) in schizophrenic patients during inhibition in the Attention Network Test (ANT). The objective of the present study was to explore whether this deficit exhibits properties of a trait or state marker of schizophrenia.
  
  
  METHODS
  Eighteen recent onset inpatients and eighteen chronic schizophrenic outpatients as well as 36 healthy controls, including a young adult and an old adult group to match recent onset and chronic illness groups for age and sex, were included. Participants were tested with ANT while 32-channel electroencephalogram was recorded and visual P3 amplitudes were analyzed. Amplitude modulation was defined as the variation of P3 amplitude at Pz as a function of ANT flanker conditions.
  
  
  RESULTS
  There were no significant behavioral between-group differences in terms of alerting, orienting, and inhibition. Mean visual P3 was significantly lower in schizophrenic patients than in healthy controls. Parietal P3 amplitude was significantly less modulated in both recent onset (-0.035) and chronic schizophrenic patients (-0.081) compared with young (-0.588; p<0.05) and older healthy controls, respectively (-0.556; p<0.05). No correlations were obtained between P3 modulation and clinical or demographic variables.
  
  
  CONCLUSIONS
  The results provide evidence that the observed deficit of visual P3 amplitude modulation is independent of duration of illness and age and may contain properties of a trait marker of schizophrenia.
authors.affiliation: Department of Psychiatry and Psychotherapy, Charité University Medicine, Campus Benjamin Franklin, Berlin, Germany. andres.neuhaus@charite.de
authors.forename: Andres H
authors.initials: AH
authors.lastname: Neuhaus
authors.forename: Eric
authors.initials: E
authors.lastname: Hahn
authors.forename: Constanze
authors.initials: C
authors.lastname: Hahn
authors.forename: Thi Minh Tam
authors.initials: TM
authors.lastname: Ta
authors.forename: Carolin
authors.initials: C
authors.lastname: Opgen-Rhein
authors.forename: Carsten
authors.initials: C
authors.lastname: Urbanek
authors.forename: Michael
authors.initials: M
authors.lastname: Dettling
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001288:Attention / Q000502:physiology; D016022:Case-Control Studies; D002908:Chronic Disease; D004569:Electroencephalography; D018913:Event-Related Potentials, P300 / Q000502:physiology*; D005260:Female; D006801:Humans; D007266:Inhibition, Psychological; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010775:Photic Stimulation / Q000379:methods; D011569:Psychiatric Status Rating Scales; D011930:Reaction Time / Q000502:physiology; D012559:Schizophrenia / Q000503:physiopathology*; D012565:Schizophrenic Psychology; D013997:Time Factors